Plain-language explanations of the measurements, sensors and numbers behind environmental monitoring.
A Protimeter moisture meter reads moisture inside building material. A hygrometer reads moisture in the air. Neither number can be converted into the other without knowing the material and its temperature.
Read Article→A hygrometer is a measuring instrument that displays relative humidity. A humidistat is a control device with a setpoint that opens or closes a circuit, and it displays nothing at all.
Read Article→A meter collapses a signal into one number a few times a second; a scope plots voltage against time at millions of samples a second, and each wins at opposite questions.
Read Article→Four decisions in a fixed order, and the reason the order matters is that the current jacks are a deliberate short circuit.
Read Article→A test lamp draws current to prove a circuit can deliver power; a meter senses voltage while drawing almost none, and that single difference explains everything else.
Read Article→A voltage tester loads the circuit and answers whether it is live; a multimeter draws almost nothing and answers how much.
Read Article→A hygrometer measures water vapour in air as a percentage; a hydrometer measures the density of a liquid as specific gravity.
Read Article→A borescope shows a lit close-up of a place your eye cannot reach, and published focal ranges of a few centimetres define the whole limit.
Read Article→Humidity sensors do degrade, and the sensing film is what ages rather than the electronics around it.
Read Article→Most consumer hygrometers publish plus or minus 3 percent RH, which is a six point window, and placement error is usually larger than the sensor error.
Read Article→A digital multimeter converts whatever you ask it to measure into a small direct voltage, digitises that voltage with an integrating converter, and scales the result into digits.
Read Article→A digital clamp multimeter is an ordinary digital meter with a hinged magnetic jaw added, so current can be read around an intact conductor instead of in series with it.
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